def StrToInt(num):
    sum=0
    i=0
    while num!='':
        sum+=int(num[len(num)-1:])*pow(10,i)
        i+=1
        num=num[:len(num)-1]
    return sum
def multiply(num1, num2):
    num1_int=StrToInt(num1)
    num2_int=StrToInt(num2)
    return str(num1_int*num2_int)


# def multiply2(num1, num2):
#     sum=0  #记录乘积结果
#     i=0
#     while num2!='':
#        c=int(num2[len(num2)-1:])
#        j=0
#        while num1!='':
#            sum += c * int(num1[len(num1) - 1:]) * pow(10, j)
#            j += 1
#            num1 = num1[:len(num1) - 1]
#         i+=1
def multiply2(num1,num2):
    sum1=0
    i=0
    while num2!='':
        c=int(num2[len(num2)-1:])
        j=0
        sum2=0
        num3=num1
        print(num3)
        while num3!='':
            print(num3[len(num3)-1:])
            sum2+=c*int(num3[len(num3)-1:])*pow(10,j)
            j+=1
            num3=num3[:len(num3)-1]
        print(sum2)
        sum1+=pow(10,i)*sum2
        i+=1
        num2=num2[:len(num2)-1]
    print(sum1)

def multiply3(num1,num2):

    pass
multiply3('200','10')








